Adsorption isotherm of a Lennard-Jones nitrogen in a carbon slitlike pore

A density functional perturbation approximation based both on second-order perturbation theory and on the pore average density has been proposed to study the adsorption hysteresis of nitrogen in a carbon slit pore. The main advantage of the present approximation is that it is computationally much simpler than the original density functional approximation based on the second-order perturbation theory of liquids, and can be applied to several model fluids confined in a strong external field in order to study their structural and thermodynamic properties. The calculated adsorption hysteresis for the confined Lennard-Jones nitrogen is in very good agreement with computer simulation, even if its accuracy slightly deteriorates for the desorption branch. The calculated equilibrium particle density distributions also compare well with computer simulations, and are better than those of a density functional theory based on the so-called mean-field approximation.     

Multimode laser emission from dye-doped hollow polymer optical fibre

Well-resolved multimode laser emission was observed for the first time from a freestanding microring cavity based on Rhodamine B dye-doped hollow polymer optical fibre by transverse pumping. Fibres with different diameters such as 180, 460, 640 and 800 μm were fabricated from a dye-doped hollow polymer preform. A blueshift in the mode structure was observed with decrease in fibre diameter leading to wide range tunability of the laser emission.     

Optimal driving strategy for a solar car on a level road

Every three years, solar cars from all over the world come toAustralia to participate in the World Solar Challenge. In 1993there were 52 cars in the race. Five cars finished within fivedays, each one breaking the previous race record and achievingan average speed exceeding 70 km/h. The performance of thesecars depends on many factors: power, aerodynamics, tractionefficiency, weight, reliability, and (not least of all) drivingstrategy. On a level road, the optimal driving strategy foran ideal car is essentially a speed-holding strategy. For areal car with inefficient energy storage, however, there aretwo distinct holding speeds. The lower speed is held when solarpower is low and must be supplemented from stored energy. Theupper speed is held when solar poler is high, and excess energyis stored.     

Computation of Current-Voltage Characteristics in a Semiconductor Device using Arc-length Continuation

This paper is concerned with the computation of semiconductordevice current—voltage characteristics. We describe analgorithm which allows the computation of characteristics bycontinuation in a parameter which approximates the arc lengthof the characteristic. The use of this parameterization allowsthe characteristic to continue beyond snap-back voltages, whilecontinuation in the voltage fails past snap-back voltages. Wediscuss the implementation of the parameterization and givea numerical example.     

MULTI-SITE PHOSPHORESCENCE OF α, β-ENONES:LEVEL INVERSION IN 6β, 19-EPOXYCHOLEST-4-EN-3-ONE BY SOLVATION AND AGGREGATION

Millisecond time-resolved emission spectroscopy was used to probe the phosphorescence kinetics of the α-β-enone 6β, 19-epoxycholest-4-en-3-one (1) as a function of concentration in several paraffinic and hydroxylic glasses at 77 K. Only in methylcyclohexane/methylcyclopentane glass at low concentration (10^?4M) does the phosphorescence decay exponentially. It is interpreted as emission from the ³n* state. Upon increasing the concentration a second emission grows which is characterized by a longer lifetime, a decreased fine structure and a hypsochromically shifted S₀→¹nπ* excitation spectrum. This phosphorescence is ascribed to ³ππ* emission of aggregates of 1. In hydroxylic glasses the phosphorescence decay is multiexponential, even at 10^?4M concentration; from emission band shapes and lifetimes it follows that both ³nπ* and ³ππ* type emissions are present, the latter increasing with the alcohol concentration in the solvent. The two types of phosphorescence have different excitation spectra: that of the structureless and long-lived ³ππ* emission is shifted to the blue in the S₀→¹nπ* region and to the red in the S⁰→¹ππ* region. This emission is ascribed to complexes of 1 with the alcoholic solvent. The results of time-resolved measurements of the circular polarization of the luminescence are consistent with the assignments given above and indicate that in the H-bonded and possibly also in the free species ³ππ* and ³nπ* states are intermixed to a considerable extent.     

ON THE COADJOINT ORBITS OF MAXIMAL UNIPOTENT SUBGROUPS OF REDUCTIVE GROUPS

Let G be a simple algebraic group defined over an algebraically closed field of characteristic 0 or a good prime for G. Let U be a maximal unipotent subgroup of G and \( \mathfrak{u} \) its Lie algebra. We prove the separability of orbit maps and the connectedness of centralizers for the coadjoint action of U on (certain quotients of) the dual \( \mathfrak{u} \)* of \( \mathfrak{u} \). This leads to a method to give a parametrization of the coadjoint orbits in terms of so-called minimal representatives which form a disjoint union of quasi-affine varieties. Moreover, we obtain an algorithm to explicitly calculate this parametrization which has been used for G of rank at most 8, except E₈.When G is defined and split over the field of q elements, for q the power of a good prime for G, this algorithmic parametrization is used to calculate the number k(U(q); \( \mathfrak{u} \)*(q)) of coadjoint orbits of U(q) on \( \mathfrak{u} \)*(q). Since k(U(q), \( \mathfrak{u} \)*(q)) coincides with the number k(U(q)) of conjugacy classes in U(q), these calculations can be viewed as an extension of the results obtained in [11]. In each case considered here there is a polynomial h(t) with integer coefficients such that for every such q we have k(U(q)) = h(q). We also explain implications of our results for a parametrization of the irreducible complex characters of U(q).     

On the Choice of Spin Functions in the AMO Method

The alternant-molecular-orbital (AMO) method as applied to the benzene molecule is reconsidered. A variational treatment was performed to determine the singlet spin function which gives the best total energy in the five-dimensional spin space available. It is found that an AMO function containing two mixing parameters and an optimized spin function gives an energy improvement over the ordinary one-parameter AMO method, utilizing a single spin function, by 0.452 eV. Optimization of the spin function alone gives an energy lowering which is 57% of this value, while a two-parameter function with the usual spin function gives 86%. On a reconsidéré l'application de la méthode des orbitales moléculaires alternantes (AMO) à la molécule de benzène. Par un calcul variationnel on a déterminé celle des fonctions singulettes de l'espace de spin à cinq dimensions, qui donne la meilleure énergie totale. On trouve qu'une fonction AMO à deux paramètres combinée à une fonction de spin optimisée donne une amélioration de l'énergie de 0.452 eV, sur la méthode AMO ordinaire à un seul paramètre et une seule fonction de spin. Une optimisation de la fonction de spin seulement donne 57% de cette valeur-ci, tandis qu'une fonction à deux paramètres avec la fonction de spin ordinaire donne 86%. Die alternierende Molekülorbitalmethode (AMO) wurde noch einmal auf das Benzolmolekül angewendet. Mit einer Variationsberechnung wird die Singulett-Spinfunktion des fünfdimensionalen Spinraum bestimmt, die die beste Gesamtenergie liefert. Man findet das eine AMO-funktion mit zwei Parametern und einer optimisierten Spinfunktion eine Energieverbesserung über die gewöhnliche AMO-Methode mit einem Parameter und einer einzigen Spinfunktion, von 0.452 eV gibt. Optimisierung der Spinfunktion allein gibt 57% dieses Wert, während eine Zweiparameterfunktion mit der gewöhnlichen Spinfunktion 86% gibt.     

A new observable to measure the top quark mass at hadron colliders

The $t\bar{t}+\mbox{1-jet} + X$ differential cross-section in proton?Cproton collisions at 7?TeV centre of mass energy is investigated with respect to its sensitivity to the top quark mass. The analysis includes higher order QCD corrections at NLO. The impact of the renormalization scale (?? _R), the factorization (?? _F) scale and of the choice of different proton??s PDF (parton distribution function) has been evaluated. In this study it is concluded that differential jet rates offer a promising option for alternative mass measurements of the top quark, with theoretical uncertainties below 1 GeV.     

EFFICIENCY IN GREAT BARRIER REEF WATER POLLUTION CONTROL: A CASE STUDY FOR THE DOUGLAS SHIRE

ABSTRACT. . Despite the lack of adequate economic evidence, water pollution from economic activities in Great Barrier Reef (GBR) catchments is often regarded excessive. In this paper marginal benefits from terrestrial (agricultural) water pollution and associated marginal marine costs from GBR degradation are estimated and used in an optimal control approach to determine optimal levels of water quality. Results, for a case study in the Wet Tropics in Australia, show that locally optimal levels of (fine sediment) water pollution are close to current levels, indicating that increased rates of (agricultural) water pollution lead to a decrease in local economic welfare. Globally optimal levels of water pollution are, however, below current levels, indicating that (inter‐) national compensation for beneficial spillovers from reduced GBR degradation can increase global economic welfare.